Returning former world No. 4 Kei Nishikori advanced to the semifinals of the Caribbean Open tennis tournament in Puerto Rico with a 6-4, 6-2 win against Australian Adam Walton on Friday.

The Japanese 33-year-old is on the comeback trail at the ATP Challenger Tour event after undergoing hip surgery in January last year and subsequently injuring his ankle during rehab.

Kei Nishikori of Japan plays against Adam Walton of Australia in the quarterfinals of the Caribbean Open tennis tournament in Palmas del Mar, Puerto Rico, on June 16, 2023. (Kyodo) ==Kyodo

Nishikori dispatched Walton in 84 minutes and will face Brazilian Gustavo Heide in the semis.

"My opponent played very hard in the first few games. He didn't make any mistakes," Nishikori said. "I can be satisfied with wrapping up in two sets against that kind of opponent."

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